1. Field
The present application relates to apparatuses and methods for transferring data, and, more specifically, it relates to a data transfer control apparatus and a data transfer control method for performing processing including processing a line of target with reference to surrounding lines.
2. Description of Related Art
Image forming apparatuses, such as a printer, may receive multivalued image data from a host PC, perform data processing including image processing on the image data with reference to surrounding pixels, and then form an image on a predetermined medium (such as paper, photographic paper, and a postcard). Image processing to be performed with reference to surrounding pixels may correspond to image processing which determines details of processing based on contents of other reference pixels disposed above and below and to the right and left of a pixel of target. Such image processing may include, for example, an enlargement process for enlarging multivalued image data and USM (unsharp mask) processing for performing a sharpening process on multivalued image data. Some image forming apparatuses may divide and store a series of image data. For example, some image forming apparatuses may divide received image data every plurality of lines and store them in a plurality of buffers or may store received image data in a memory region where the data is stored up to a lower limit of the memory region and then to a top part of the memory region like a ring buffer. When data are divided and stored, image processing may be performed by using a memory region excluding a memory region where received image data is being stored. Thus, data reception and image processing may be performed in parallel.
In this case, when reference image data are stored at divided storage locations, it may be required to read image data from the plurality of storage locations where they are stored as if a series of image data are stored and supply them to an image processing unit.
Accordingly, Japanese Laid-Open Patent No. 8-166921 discloses a method including setting two memory addresses, starting data transfer from a first address, and, if it is determined that the data transfer has finished, restarting data transfer from a second address. According to this method, image data divided into a plurality of memory regions may be transferred as a series of image data.
However, the data transfer method disclosed in Japanese Laid-Open Patent No. 8-166921 may change the transfer destination address only once in the middle of the processing and may not handle a case where image data divided and stored as described above are required to be transferred several times as a series of image data. Therefore, for example, in a case where image data are divided every plurality of lines to generate a plurality of bands and band processing is performed on each of the bands, the memory region to be read is changed several times within one band, which may require resetting a parameter for data transfer every time the memory region is changed.
Accordingly, a method may be considered which provides an overlap area at a boundary of a memory region, and image data is arranged in the overlap area for continuous transfer of image data. However, such an overlap area may disadvantageously require an extra memory. A load may be imposed on a CPU by copy processing for copying target image data from one memory region to an overlap area in another memory region, and memory access for the copy processing.